Wheatstone E-SAT, Technical Manual

Page: 45 / 126

page 2 – 11
E-Series Network / Apr 2007
H A R D W A R E
Digital Output Card (DO-NC4)
Overview
Each Digital Output card provides 4 physical AES-3 formatted outputs.
An Audio Configuration form in the supplied XPoint software allows the
user to set attributes for the output channels, including signal name,
location, and Stereo/Mono. The 4 AES outputs are configured in software
at the factory to be stereo destinations.
Each output card listens for connection commands from the
E-WHEATNET CPU, and then uses this information to connect the
appropriate sources to their selected output channels. The selected audio
data is fed to AES transmitters which format the 24 bit audio data according
to the AES-3 standard.
Note: While it is possible to split the 4 stereo AES outputs into 8 mono
channels, there are still only 4 physical wires, each containing the
2-channel AES formatted data.
AES Output Interface
The balanced digital audio outputs on the DO-NC4 card are transformer
coupled and exhibit a nominal output impedance of 110 Ohm. This
interface operates at a nominal output voltage of 5V p-p and conforms to
the AES-3 1992 electrical specification. The DO-NC4 output cards operate
at unity gain and transmit 24bit audio data word lengths at the system
sample rate, which can be set to 44.1 kHz or 48 kHz. Optionally, the E-
WHEATNET External AES Sync input may be used to slave the system to
a user provided 44.1 kHz or 48 kHz reference rate. Please refer to the E-
WHEATNET hardware section for details on external synchronization.
The digital output signal reference level is -20dBFS. A +4dBu analog
input signal yields a -20dBFS digital output signal. Channel Status
implementation complies with rules for “standard implementation” as
described in the AES-3 1992 specification.